Actinomycetes and earthy-musty odorous compounds in brackish fishponds in Tianjin, China

The presence of the odorous compounds, 2-methylisoborneol (MIB) and geosmin, as well as causative microorganisms in brackish intensive cultivation fishponds in Tianjin, China that had a severe earthy-musty odor were evaluated. The results revealed that MIB was the primary odorous compound present in the Tianjin fishponds, with a concentration ranging from 0.53-5302.7 ng.L-1. Furthermore, the concentration of MIB was found to be closely correlated with the gross biomass of actinomycetes in the water, which ranged from 10.67-1528.24 x 10(6) cfu.ml(-1). Therefore, the sequences of the 16 SrRNA and morphological characteristics of the actinomycetes in the brackish fishponds were investigated. The results revealed that the actinomycetes in the brackish fishponds included 9 species of common and dominant actinomycetes belonging to 4 genera. Of these genera, Streptomyces were the dominant species, and Streptomyces, Nocardioides and Micromonospora were the most common species in the fishponds evaluated. Next, the ability of each of the isolated Streptomyces to produce MIB was measured under laboratory culture conditions. Streptomyces Sp2 was found to have a strong ability to produce MIB, which indicates that this strain may be the primary source of the earthy-musty odor reported in brackish intensive cultivation fishponds in Tianjin, China.

Monte Carlo simulation of the modulated effect induced by the dislocation to the quantum dot growth

Performing an event-based continuous kinetic Monte Carlo simulation, we investigate the modulated effect induced by the dislocation on the substrate to the growth of semiconductor quantum dots (QDs). The relative positions between the QDs and the dislocations are studied. The stress effects to the growth of the QDs are considered in simulation. The simulation results are compared with the experiment and the agreement between them indicates that this simulation is useful to study the growth mode and the atomic kinetics during the growth of the semiconductor QDs. (c) 2006 Elsevier Ltd. All rights reserved.

The status, limits and countermeasures in the development of the silicon microelectronics industry

In this paper.. the status and limits in the development of the silicon microelectronics industry are presented briefly. The key countermeasures given are use of the new structure materials and the new device structures.

Effect of the implantation of fluorine on the mobility of channel electron for partially depleted SOI nMOSFET

The mobility of channel electron, for partially depleted Sol nMOSFET in this paper, decreases with the increase of implanted fluorine dose in buried oxide layer. But, the experimental results also show that it is larger for the transistor corresponding to the lowest implantation dose than no implanted fluorine in buried layer. It is explained in tern-is of a "lubricant" model. Mien fluorine atoms are implanted in the top silicon layer, the mobility is the largest. In addition, a positive shift of threshold voltage has also been observed for the transistors fabricated on the Sol wafers processed by the implantation of fluorine. The causes of all the above results are discussed.

High performance resonant tunneling diode on a new material structure

A new material structure with Al0.22Ga0.78As/In0.15Ga0.85As/GaAs emitter spacer layer and GaAs/In0.15Ga0.85As/GaAs well for resonant tunneling diodes is designed and the corresponding device is fabricated. RTDs DC characteristics are measured at room temperature. Peak-to-valley current ratio (PVCR) is 7.44 for RTD Analysis on these results suggests that the material structure will be helpful to improve the quality, of RTD.

Electronic states of InAs verfically-assembled quantum disks in magnetic fields and two-electron quantum-disk qubit

We have studied the single-electron and two-electron vertically-assembled quantum disks in an axial magnetic field using the effective mass approximation. The electron interaction is treated accurately by the direct diagonalization of the Hamiltonian matrix. We calculate the six criergy levels of single-electron quantum disks and the two lowest energy levels of two-electron quantum disks in an axial magnetic field. The change of the magnetic field as an effective potential strongly modifies the electronic structures. leading to splittings and crossings between levels The results demonstrate the switching between the around states with the total spins S = 0 and S = 1. The switching results in a qubit allowed to fabricate by current growth techniques.

Influence of fluorine on radiation-induced charge trapping in the SIMOX buried oxides

Charge trapping in the fluorinated SIMOX buried oxides before and after ionizing radiation has been investigated by means of C-V characteristics. Radiation-induced positive charge trapping which results in negative shift of C-V curves can be restrained by implanting fluorine ions into the SIMOX buried oxides. Pre-radiation charge trapping is suppressed in the fluorinated buried oxides. The fluorine dose and post-implantation anneal time play a very important role in the control of charge trapping.

Radiation response of partially-depleted MOS transistors fabricated in the fluorinated SIMOX wafers

Ionizing radiation response of partially-depleted MOS transistors fabricated in the, fluorinated SIMOX wafers has been investigated. The experimental data show that the, radiation-induced threshold voltage shift of PMOSFETs and NMOSFETs, as well as the radiation-induced increase of off-state leakage current of NMOSFETs can be restrained by implanting fluorine ions into the buried oxide of SIMOX wafers.

A simulation model of body contact structure in PD SOI analogue circuit

As a solution of accurate simulation of the body effect in PD SOI analogue circuit, a simulation model of distributed body contact resistance and parasitical capacitance is presented. Based on this model, we have designed and simulated a sense amplifier that applied to V a 0.8um PD SOI 64K SRAM.